Objection 1. It would seem that the reason for divorce was hatred for the wife. For it is written (Malachi 2:16): "When thou shalt hate her put her away." Therefore, etc.
Objection 2. Further, it is written (Deuteronomy 24:1): "If... she find not favor in his eyes, for some uncleanness," etc. Therefore the same conclusion follows as before.
Objection 3.On the contrary, Barrenness and fornication are more opposed to marriage than hatred. Therefore they ought to have been reasons for divorce rather than hatred.
Objection 4. Further, hatred may be caused by the virtue of the person hated. Therefore, if hatred is a sufficient reason, a woman could be divorced on account of her virtue, which is absurd.
Objection 5. Further, "If a man marry a wife and afterwards hate her, and seek occasions to put her away"* alleging that she was not a virgin when he married her, should he fail to prove this, he shall be beaten, and shall be condemned in a hundred sicles of silver, and he shall be unable to put her away all the days of his life (Deuteronomy 22:13-19). [The rest of the passage is apparently quoted from memory.] Therefore hatred is not a sufficient reason for divorce.
I answer that, It is the general opinion of holy men that the reason for permission being given to divorce a wife was the avoidance of wife-murder. Now the proximate cause of murder is hatred: wherefore the proximate cause of divorce was hatred. But hatred proceeds, like love, from a cause. Wherefore we must assign to divorce certain remote causes which were a cause of hatred. For Augustine says in his gloss (De Serm. Dom. in Monte i, 14): "In the Law there were many causes for divorcing a wife: Christ admitted none but fornication: and He commands other grievances to be borne for conjugal fidelity and chastity." Such causes are imperfections either of body, as sickness or some notable deformity, or in soul as fornication or the like which amounts to moral depravity. Some, however, restrict these causes within narrower limits, saying with sufficient probability that it was not lawful to divorce a wife except for some cause subsequent to the marriage; and that not even then could it be done for any such cause, but only for such as could hinder the good of the offspring, whether in body as barrenness, or leprosy and the like, or in soul, for instance if she were a woman of wicked habits which her children through continual contact with her would imitate. There is however a gloss on Deuteronomy 24:1, "If... she find not favor in his eyes," which would seem to restrict them yet more, namely to sin, by saying that there "uncleanness" denotes sin: but "sin" in the gloss refers not only to the morality of the soul but also to the condition of the body. Accordingly we grant the first two objections.
Reply to Objection 3. Barrenness and other like things are causes of hatred, and so they are remote causes of divorce.
Reply to Objection 4. No one is hateful on account of virtue as such, because goodness is the cause of love. Wherefore the argument does not hold.
Reply to Objection 5. The husband was punished in that case by being unable to put away his wife for ever, just as in the case when he had corrupted a maid (Deuteronomy 22:28-30).
Source: Summa Theologica (New Advent)